TECHNIQUES OF TELEVISON BROADCASTING (F)  sent 

SANTI PADA CHAKRABORTY,   

              Fellow Member of Istituition Of  ngineers  (India) and Ex-Superintending

             Engineer(elect), WBSEB. (spc_2008@yahoo.com)                  

    1. Terretrial Televison Broadcasting:-  Terretrial Televison Broadcasting is the type of televison broadcasting in which the TV signal is trasmitted by radio wave to the TV receiver from a terrestrial (earth based) transmitt           

     Television broadcast is great source  of entertaiment and multimeadia industry.It broadcasts thousands various programs like TV serials, news program, cinema sports for enjoyment thousands people of the country

  Broadcasting means airbrone transmission of EM audio signal (radio) or audio visual signal (television)which are  received by TV. Major components of television broadcasting are image sourse, sound sourse, a transmitter, a receiver, a display device and a sound device

  Image sourse is the program. This is  movie, TV show, news program etc.  This is video  sourse excluding sound,  recorded in VCR  and at present in DVD or PVR.   Sound source is audio signal of programs, movie, news program, TV show etc. Sound may be mono, stereo or surround sound.

   Transmitter sends more than one signal (TV channel) at a time. A transmitter modulates both picture and sound into one signal then transmit by air wave over a wide area for TV set to receive. All  TV set tuner can select specific channel. Each channel is transmitted in its own frequency which TV set can receive by tuning.

    Television signal can be telecasted in vaious ways such as   (1)Terrestrial Television Broadcasting, (2). Satellite TV Broadcasting  (3)Cable TV Broadcasting (4).  IPTV Broadcasting, (5) Internet TV Broadcasting. And next generation broadcast are  1. Digital Terrestrial Broadcasting, 2. HD TV Broadcasting,  3. 4K TV Broadcasting and 4. 3D TV Broadcasting.   

er through a televison station  and an antenna which is connected to the TV. The  broadcast is analog signal. Terrretrial TV is different from newer technologies of satellite TV  and cable TV.

    Terrestrial television was the first technology used for television broadcasting, with the first long-distance public television broadcast. It  began in 1927 in Amerca. BBC started in1930. At first TV was in black and white untill 1960 then colour TV started 

    2. Satellite TV Broadcasting:-  Satellite televison is called direct to home (DTH) televison. Digital broadcast  satellite programming is in K_u band frequency range  10GHz io 14GHz . In DTH channels/programs are directly distributed via satellites to subscribers’  home without intervention of cable operator. The signals are transmitted in K_u band and are received  through small dish antenna about 45 cms in dia.  in building roof-top  or on the wall facing clear south  and one indoor set-top box which will allow viewing of demultiplexesd signals from DTH channel bouque on TV set. In DTH service large number of channels  are digitally compressed, encrypted  and uplinked to a high power satellite and it beamed down over a territory..

    As  the DTH telecast is digital, user will get all benefits of digital transmission like internet, e-mail , e-commerce and interactive multimedia. Programmes in DTH have higher resolution, pictures and better audio quality than traditional analog signals. In addition,  as the digital technology frequency spectrum is highly efficient, the number of TV channels that can be broadcast  is higher than in analog technology. The operator can give supply sufficient number of subscribers.

     Most of the DTH services all over the world and India provide paid DTH service. In paid service, the DTH operators uplink the encripted signaL to the satellite. DD Direct+ is an Indian free-to-air digital satellite television owned by Doordarshan, providing digital video and audio. Doordashan India give free distribution of 63 digital channenls.

    The satellites rotate in geosationery orbit that means they remain in one place relative to earth. Each satellite is launched into space  which rotate at speed of  about 7000 mile per hour (11000 Km per hour)  at a height of approximately 22200 miles (35700 Km) above earth. At this height and speed , the satellite  revolves around earth once every 24 hour - the same period of time earth take to make one full rotation. That means the satellite keeps pace with our revolving Earth and it remains exactly n same place above earth always. So only once  dish is to be directed at the satellite and from then on  it picks the signal without adjustment.

   There are five major components  in a direct to home (DTH) satellite system: the programming source, the broadcast center, the satellite, the satellite dish and the receiver.  

     Broadcast centre is the central hub. Central hub receives TV signal from different programmimg sources, converts  all signal in uncompressed digital stream. Huge uncompressed data about 270 Mbps for each channel compresses by  MPEG-2 compression. 270 Mbps stream is compressed to 3 or 10 Mbps. With digital compression a saellite can transmit 200 channels. Without compression only 30 channels can be transmitted. After Compression scramble  it and  transmit broadcast signal to the satellite used by it or to multiple satellite which then  amplifies and  rebroadcast those signal back to earth across large area. Subscriber’s satellite dish picks up the signal from satellite (or multiple satellites in same parts of the sky) and  sends  signal to set-top box inside home which is  connected to TV. The set top box processes the signal.

    After compression provider encrypt so that nobody can access it for free. Encryption scramble data such that it can only be decrypted if user has correct decoding satellite receiver with decryption algorithm and security keys.

    Most of the DTH Services, operating all over the world and in India, provide paid DTH Service. In the paid service, the DTH operators by choosing the bunch of various desired TV channels and  the payment plan, subscribers are given a key-code to decode/decrypt      

     Dish:- it is a special kind of antenna to focus on specific broatcast satellite. It consists of a parablic (bowl-shaped) surface and a central feed horn in the focus point of dish. The dish send signal to a set top box and  then sent to the televison.

     Set top box:- Set-top-box is the end component of DTH Televison which descramble the encryted signal. It contains  a chip. Provider communicate with the chip by sending  signal through satellite  and by electronic counter measure (ECM)  prevents illegal consumers to receive channels. Set-top-box by MPEG-2 converter converts  digital signal to analog fomate which anlaog TV can receive.

     Programming:- Channels for broadcast from broadcasting cente are not created  by satellite TV (DTH) providers. They get proramming from International turnaround channels such as HBO, ESPN,and CNN, STAR TV , SET,B4H etc) and local channels (SaBe TV, Sahara TV , Doordarshan , etc. Most of the turn arround channels also provide for cable televison. DTH provider act as broker.        

    3.Cable Television broadcasting:- Cable TV  has  maximum user worlwide. Network companies beam TV signals  via satellites through large dish. Cable operatotrs ( or Multi-Systrem Operators (MSO). In their  head ends (control center for cable network) aggregate TV channels received from different satellites. They mix this with contents  received from other sourses such as broadband connections, local channels etc, to form bouquet of channels and then they distribute these to subsribers homes using coaxial cable or optical cable.

    Cable TV distrbute number of televison channels (as many as 500 channels or as per their capacity). Many pay channels can be transmitted through one coaxial cable by technique- frequency divison multiplexing. At headend TV channels translate frequency signals. Uplink and downlink signals do not interfare  for giving  them differennt frequency slot. Cable televison offers variety of programs such as news, sports, movies, cooking, home shopping,and family viewing serials. For this provider get money from suscribers and advertisement

     At subsriber’s home cable company either give connection  to TV set or set-top box.  TV or set-top box traslates the desird channel back to original frequency and it is displayed on TV. On conversion to cable or satellite TV old TV set can be used. Because set-top box in cable and satellite TV will do the digital conversion.

     Use of different frequency in channels allows many channels to  be distributed thorgh same cable, without separate wire for each channels. The network takes the form of tree, with trunk carries signal in main lines, the branches carry signals to building  and finally arms carry signal to suscribers.

    Coaxial cable can carry 100 TV channels but signals decay with distance, hence require to amplify for renewing signal periodically. Many operator use optical cable for trunk  to minimise  noise and eliminate use of amplifire as optical fibre has more capacity and allows more programs to be carried without signal loss or noise. In optical cable and coaxial cable joint light signal  of optical cable is coverted to radio frequency electrical signal and then sent to set top box by coxial cable. Trasmission signals are encrypted  and sent to viewers’  set-top- box to receive and decrypt the signal.     

    As  per policy of Government shift to digital system from analog in Delhi Kolkata Mumbai, Chennai  metros and big cities are done. In 3^rd and 4^th phase 11crore will now be undertaken and gadually entire country will be digitised.    

     As per TAM Annual universe report-2014 India has over 277 million public (out of 312 million) who have televison sets,of which 145 million have access to  cable or satellite TV out of which 78 million are  DTH subscriber. Digital TV user have grown 32% since 2013 migrating from terrestrial and analog broadcasts.

   Now govt will give license to 700 more MSOs. Now slightly more than 600 exists. As per policy of Government of India, viwers would get access to digital TV through set-top box (STB).  India at present has more than 823 TV channels covering all the main languages which will increase. 

    4.Internet Protocol Television broadcasting:- In Internet Protocol Televison (IPTV) broadcasting televison programs are delivered using internet over a packet-switched network like LAN  Or  internet instead of being delivered througjh terretrial, stellite and cable TV.

   In IPTV Head end live TV channels and channels received from different sources including satellite are decryted.  Contents (channels) are than compressed in MPEG-2 or MPEG-4 formate. Programs or channels are then packed in a transport stream (MPEG-Ts) and packetised and broadcast in IP network. IP packets are transported to home in broadband DSL A splitter seprates out TV from regular broadband.

   In IPTV can stream media in small batches from source, not like downloading media. As a result, user can start playing media player data (movie) without downloading full file. Vedio on Demand (VoD)  program is encrypted and stored in VoD server with protection mechanism. VoD server is not centralised but distributed. Subscribers receive Vod programs through unicast streaming. Through set top box  Subscriber can  receive broadcsted channels but can receive only tuned channels. Subscribers can  navigate Live channel, cinema, Vedio on Denand game etc  through  interactive interface. 

   In IPTV network Set top box is a small coomputer, gives two way communication on an IP network  decoding the video streaming media.

IP set top box have built in network interface that can be ethernet, Wi-Fi, or  any of the existing  netwok technologies, which enable to create high speed upto 1Gbps in  local area networking existing in home wiring (power line, phone line, coaxial cable).

    In India IPTV was launched by Airtel and MTNL and BSNL through tie up with AKSH and are available in most of the main cities of the country. In southern India UF group plans to offer such as movies on demand, vedio conferencing, media plater, e-learning etc on their single IPTV set top box.

   In India at present IPTV is available with subscription in main cities as broadband internet connection is available in urban areas.

   Airtel IPTV is available in New Delhi and Bangalore which has about 175 TV channels.

    In IPTV time –shifted television ( TV show which have been broadcast few hours before or few days before can be be replayed), Star-over TV  ( at present TV show can replay from beginning) and except video on demand (VOD) TV programming,  live TV reception is good.  

    5. Internet television broadcasting:-Internet television (or online television) broadcasting is the digital distribution of television content via the Internet. Internet television deliver television programs and other video content over the Internet by video streaming technology by major television broadcasters. It is different from traditional systems like terrestrial, cable and satellite. Internet itself is received by terrestrial, cable or satellite methods.

      Internet television should not to be confused with Smart TV, IPTV or with Web TV.  Internet TV works by connecting an Internet-enabled device to the TV and streaming video content from select Internet sites through the device in the TV. Some TVs are already Internet-enabled and do not require the addition of a separate device.

       Current providers of Internet television use various technologies such as peer-to-peer (P2P) technologies, VoD systems, and live streaming . BBC iPlayer use  the Adobe Flash Player to provide streaming-video clips and other software provided by Adobe for its download service. CNBC, Bloomberg Television and Showtime use live-streaming method  from BitGravity to stream live TV  to paid subscribers using a standard http protocol and many  mobile devices. Samsung TV has also announced their plans to provide streaming methods including 3D Video on Demand through their Explore 3D service. There are various other methods.             

     Other new generation techniques are given below.

    Digital Terrestrial Television (DTTV or DTV) is a technological evolution of broadcast television. DTTV broadcasts land-based (terrestrial) signals. The advantages of digital terrestrial television, are similar to digital versus analog  signal in  cable TV, satellite TV, and all telecommunications.. It gives better quality images, and lower operating costs for broadcast and transmission but  initial upgrade costs are to be met. Terrestrial  digital television (DTV) technology uses an aerial to broadcast signal to a conventional television antenna (or aerial) instead of a satellite dish or cable television connection.

    DTTV is transmitted on radio frequencies through land in the same way as standard analog television. The primary difference being the use of multiplex transmitters to allow reception of multiple channels on a single frequency range (such as a UHF or VHF channel) known as subchannels.

 

.    Digital Television is  the future of broadcsting system. It  provides interference free  television reception and improved picture & sound quality. 

     Digital Terrestrial Television (DTT) offers numerous advantages over its analog counterpart such as multi-channel operation, reception quality is superior and uniform, reception is possible in moving vehicles,  less power requirement. In addition, DTT is highly spectrum efficient. Ten to 12 channels can be accommodated in the bandwidth required for a single analogue channel. 

     Parallel technologies such as Digital Cable, DTH, IPTV and internet TV  broadcasting would prevail, terrestrial transmission will have to continue on account of various reasons.

    public service broadcaster, Doordarshan  will  migrate to DTT, abbreviation for "Digital Video Broadcasting — Terrestrial"; first broadcast in the UK in 1998. This system transmits compressed digital audio, digital video and other data in an MPEG transport stream, using coded orthogonal frequency-division multiplexing (COFDM or OFDM) modulation.

    In India Terrestrial Television service would be in DVB-T2 technology; this is a new technology that will replace analogue terrestrial television. Digital Terrestrial Television can be used for broadcast digital TV and radio channel. In India Prasar Bharati adopted DVB-T2 technology for Digital Terrestrial Television service.

    Digital Terrestrial Television (DVB-T2) service is better. It gives

crystal clear picture and sound in digital Quality, Surround Sound quality. Maximum channel can be broadcast, support mobile and portable device reception and Digital Radio service can be transmitted.

    HDTV Broadcasting:- Till now 23 full True HD (1920 X 1080 pixels resolution) channels are avalable in India.  6 DTH providers are giving HDTV such as Dish TV, Tata Sky, Sun Direct, Reliance Digital and Airtel Digital and Vediocon D2H. Full HD is a resolution of 1920x1080 pixels. Its screen is broad, aspect ratio 16:9 horraizotal resolution 1920 dot and vertical 1080, frame resolution 1920x1080 or 2073600 pixel. DVD video uses standard definition (SD) and Blu-Ray video uses Full HD.

 Satellite service provider  get programming from different sources. Then channels/ programs are transmitted to the subsscrbers’ home through satellite. HDTV satellite works in the same way as standard Satellite TV, mentioned above.  Service providers  get programs from different sources. Then these are compressed  and decrypted and transmitted by a large dish to  a satellite which revolves in geosynchronous orbit. That means satellite rotate in same speed as earth. Always remans above earth in same place.

   Satellite receives signal and retransmit back to the earth in large region. Subscribers dish pick up signal and sent to set top box. Set top box encrypt signal  and to TV to view      

      4K TV broadcast:- New generation 4K TV Broadcasts is coming to India. In August 2012, Sony announced  the technology as "4K Ultra High Definition". Most other TV manufacturers use this  term.  UHD is used interchangeably with 4K for describing TVs, source devices, accessories or content. CNET say "4K" instead of "UHD", and Google support this.

      Last year we have seen the rise of a new HDTV technology called 4K  Or if you use its official name, Ultra High Definition (UHD).

UHD is an "umbrella term" its resolutions is higher (more pixels) than HDTV. This year, improvements occure in new TVs and content is 4K resolution.4K is the future. But not until it become commercially available (and affordable), also TVs require are 120-inches or larger, and content and ads should also be available.

   Ultra-HD, 4K content generally  uses 3840x2160 pixels, four times sharper than HD.  4K picture  look stunning,  it has more realistic color and higher frame rates. Getting the contents are challenge.  

   Tata Sky and Videocon D2H have been broadcasting select matches of the ongoing ICC Cricket World Cup in 4K. Both operators have a several HD channels and a single 4K channel each. Videocon D2H  demo 4K content tried before. The 4K channel on Videocon runs a small amount of repetitive content for the time being, Tata Sky's service was set up on a 65-inch Sony 4K television, and has similar content. Both are broadcasting key games of the 2015 Cricket World Cup in 4K, and we had a chance to watch the India-Bangladesh quarter-final match in 4K.

   4K/UHD means the TV's screen has a minimum resolution of 3,840 pixels wide and 2,160 pixels high, making it  equivalent to two 1080p screens in height and two in length. Full HD is a resolution of 1920x1080 pixels.

   Ultra-HD, 4K content usually uses 3840x2160 pixels, four times sharper than HD. Though  DVD video uses standard definition and Blu-Ray video uses Full HD.

     Another resolution, known as 4Kx2K (4,096x2,160 pixels), is used by some projectors and many professional cameras. It also falls under 4K/UHD. 4K is expensive like 3D TV but the picture quality is so clear that it appears as though it is 3D; as if it popping off the TV.

       4K TV has 2 set top boxes.  DTH provider offer 1 channel. Channel feed is divided into 4 quadrant, each quadrant has its own relay. From satellite satellite dish receives 4 separete feed and signal is sent to 4K set top box which compile feeds into 1 image and sent to 4K TV. If broadcaster or satellite operator’s Bandwidth is dropped flaw in picture is observed. For time being fault in trasmission one quadrant of TV screen freezes, other quadrants remain perfect. Later TV become normal.

 Vedeocon D2H ও Tata Sky বেশী 4K content (বিষয়), টেলিভিসন show ও মুভি আনার চেষ্টা করছে।  

     3D television (3DTV) Broadcasting:- The evolution of technology in television has escalated dramatically within the last few years. From HD to flat screens to 3D TV. 3D is television that conveys depth perception. Picture appears as if pops out of TV. Today most of the TV use stereoscpic technique , similar to  the method  our eyes works. Our eyes are like two lenses, each eye collects  same picture from different angle. Brain process these pictures and combine two picture to make 3D picture. Autostereoscopic without the need of glasses. The picture jumps off the screen and makes it appear before us. Proccessing occurs so rapidly that we can not undersatand it is happening. other methods also exist for picture display 3D.  All know about old Anagylph 3D method. It requires spectacle to view 3D cinema to perform blue-red polarisation of image. Our right eye sees image through blue filter and left eye at a seprate angle through red filter. By clouring right eye glass of a powerless spectacle with blue colour and left glass with red 3D TV can be viwed by it, but picture must be 3D.  

   According to DisplaySearch 3D televisions shipments totaled 41.45 million units in 2012. In 2013 the number of 3DTV viewers started to come down. In 3DTV ads and programming contents are also not avalailable.

    3D broadcast in the UK was an episode of the weekly science magazine  on 31st January 2010, BSKYB  broadcast first time in  the world to show a live sports event in 3D when Sky Sports broadcasts a football match. (3D image)

     In India Videcon has D2H 3D TV. MOBILESTAR broadcast  3D TV channel first time in India.